Internet Engineering Task Force H. Singh
Internet-Draft W. Beebee
Intended status: Informational Cisco Systems, Inc.
Expires: January 12, 2012 C. Donley
CableLabs
B. Stark
ATT
O. Troan, Ed.
Cisco Systems, Inc.
July 11, 2011
Advanced Requirements for IPv6 Customer Edge Routersdraft-ietf-v6ops-ipv6-cpe-router-bis-01
Abstract
This document continues the work undertaken by the IPv6 CE Router
Phase I work in the IETF v6ops Working Group. Advanced requirements
or Phase II work is covered in this document.
Status of this Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on January 12, 2012.
Copyright Notice
Copyright (c) 2011 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
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Internet-Draft IPv6 CE router Advanced Requirements July 20111. Introduction
This document defines Advanced IPv6 features for a residential or
small office router referred to as an IPv6 CE router. Typically
these routers also support IPv4. The IPv6 End-user Network
Architecture for such a router is described in [RFC6204]. This
version of the document includes the requirements for Advanced
features.
1.1. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119].
2. Terminology
End-user Network one or more links attached to the IPv6 CE
router that connect IPv6 hosts.
IPv6 Customer Edge router a node intended for home or small office
use which forwards IPv6 packets not
explicitly addressed to itself. The IPv6
CE router connects the end-user network to
a service provider network.
IPv6 host any device implementing an IPv6 stack
receiving IPv6 connectivity through the
IPv6 CE router
LAN interface an IPv6 CE router's attachment to a link in
the end-user network. Examples are
Ethernets (simple or bridged), 802.11
wireless or other LAN technologies. An
IPv6 CE router may have one or more network
layer LAN Interfaces.
Service Provider an entity that provides access to the
Internet. In this document, a Service
Provider specifically offers Internet
access using IPv6, and may also offer IPv4
Internet access. The Service Provider can
provide such access over a variety of
different transport methods such as DSL,
cable, wireless, and others.
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Internet-Draft IPv6 CE router Advanced Requirements July 2011
WAN interface an IPv6 CE router's attachment to a link
used to provide connectivity to the Service
Provider network; example link technologies
include Ethernets (simple or bridged), PPP
links, Frame Relay, or ATM networks as well
as Internet-layer (or higher-layer)
"tunnels", such as tunnels over IPv4 or
IPv6 itself.
3. Conceptual Configuration Variables
The CE Router maintains such a list of conceptual optional
configuration variables.
1. Enable an IGP on the LAN.
2. Configure 6rd configuration.
3. Configure IPv6 for 6rd to have IPv6 traffic go to the 6rd Border
Relay vs. directly to peers.
4. Architecture
This document extends the architecture described in [RFC6204] to
cover a strictly larger set of operational scenarios. In particular,
QoS, multicast, DNS, routed network in the home, transition
technologies, and conceptual configuration variables. This document
also extends the model described in [RFC6204] to a two router
topology where the two routers are connected back-to-back (the LAN of
one router is connected to the WAN of the other router). This
topology is depicted below:
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Internet-Draft IPv6 CE router Advanced Requirements July 20115. Advanced Features and Feature Requirements
The IPv6 CE router will need to support connectivity to one or more
access network architectures. This document describes an IPv6 CE
router that is not specific to any particular architecture or Service
Provider, and supports all commonly used architectures.
5.1. DNS
D-1: The CE Router MAY include a DNS server authoritative for .local
to handle local queries. If the service provider specifies one
or more DNS resolvers in DHCP configuration options, the CE
router SHOULD forward all non-local DNS queries unchanged to
those servers. The CE Router MAY also include DNS64
functionality which is specified in [RFC6147].
5.2. Multicast Behavior
This section is only applicable to a CE Router with at least one LAN
interface. A host in the home is expected to receive multicast
video. Note the CE Router resides at edge of the home and the
Service Provider, and the CE Router has at least one WAN connection
for multiple LAN connections. In such a multiple LAN to a WAN
toplogy at the CE Router edge, it is not necessary to run a multicast
routing protocol and thus MLD Proxy as specified in [RFC4605] can be
used. The CE Router discovers the hosts via a MLDv2 Router
implementation on a LAN interface. A WAN interface of the CE Router
interacts with the Service Provider router by sending MLD Reports and
replying to MLD queries for multicast Group memberships for hosts in
the home.
The CE router SHOULD implement MLD Proxy as specified in [RFC4605].
For the routed topology shown in Figure 1, each router implements a
MLD Proxy. If the CE router implements MLD Proxy, the requirements
on the CE Router for MLD Proxy are listed below.
WAN requirements, MLD Proxy:
WMLD-1: Consistent with [RFC4605], the CE router MUST NOT implement
the router portion of MLDv2 for the WAN interface.
LAN requirements, MLD Proxy:
LMMLD-1: The CPE Router MUST follow the model described for MLD
Proxy in [RFC4605] to implement multicast.
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Internet-Draft IPv6 CE router Advanced Requirements July 2011
LMMLD-2: Consistent with [RFC4605], the LAN interfaces on the CPE
router MUST NOT implement an MLDv2 Multicast Listener.
LAN requirements:
LM-1: If the CE Router has bridging configured between the LAN
interfaces, then the LAN interfaces MUST support snooping of
MLD [RFC3810] messages as per [RFC4541] .
5.3. Routed network behavior
CPE Router Behavior in a routed network:
R-1: One example of the CPE Router use in the home is shown below.
The home has a broadband modem combined with a CPE Router, all
in one device. The LAN interface of the device is connected to
another standalone CPE Router that supports a wireless access
point. To support such a network, this document recommends
using prefix delegation of the prefix obtained either via IA_PD
from WAN interface or a ULA from the LAN interface. The
network interface of the downstream router MAY obtain an IA_PD
via stateful DHCPv6. If the CPE router supports the routed
network through a vendor specific automatic prefix delegation,
the CPE router MUST support a DHCPv6 server or DHCPv6 relay
agent. Further, if an IA_PD is used, the Service Provider or
user MUST allocate an IA_PD or ULA prefix short enough to be
delegated and subsequently used for SLAAC. Therefore, a prefix
length shorter than /64 is needed. The CPE Router MAY support
and IGP in the home network.
/-------+------------\ /------------+-----\
SP <--+ Modem | CPE Router +--+ CPE Router | WAP + --> PC
\-------+------------/ \------------+-----/
WAP = Wireless Access Point
Figure 2.
5.4. Transition Technologies Support5.4.1. Dual-Stack(DS)-Lite
Even as users migrate from IPv4 to IPv6 addressing, a significant
percentage of Internet resources and content will remain accessible
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Internet-Draft IPv6 CE router Advanced Requirements July 2011
only through IPv4. Also, many end-user devices will only support
IPv4. As a consequence, Service Providers require mechanisms to
allow customers to continue to access content and resources using
IPv4 even after the last IPv4 allocations have been fully depleted.
One technology that can be used for IPv4 address extension is DS-
Lite.
DS-Lite enables a Service Provider to share IPv4 addresses among
multiple customers by combining two well-known technologies: IP in IP
(IPv4-in-IPv6) tunneling and Carrier Grade NAT. More specifically,
Dual-Stack-Lite encapsulates IPv4 traffic inside an IPv6 tunnel at
the IPv6 CE Router and sends it to a Service Provider Address Family
Translation Router (AFTR). Configuration of the IPv6 CE Router to
support IPv4 LAN traffic is outside the scope of this document.
The IPv6 CE Router SHOULD implement DS-Lite functionality as
specified in [I-D.ietf-softwire-dual-stack-lite].
WAN requirements:
DLW-1: To facilitate IPv4 extension over an IPv6 network, if the CE
Router supports DS-Lite functionality, the CE Router WAN
interface MUST implement a B4 Interface as specified in
[I-D.ietf-softwire-dual-stack-lite].
DLW-2: If the IPv6 CE Router implements DS-Lite functionality, the
CE Router MUST support using a DS-Lite DHCPv6 option
[I-D.ietf-softwire-ds-lite-tunnel-option] to configure the
DS-Lite tunnel. The IPv6 CE Router MAY use other mechanisms
to configure DS-Lite parameters. Such mechanisms are outside
the scope of this document.
DLW-3: IPv6 CE Router MUST NOT perform IPv4 Network Address
Translation (NAT) on IPv4 traffic encapsulated using DS-Lite.
DLW-4: If the IPv6 CE Router is configured with a public IPv4
address on its WAN interface, where public IPv4 address is
defined as any address which is not in the private IP address
space specified in [RFC1918] and also not in the reserved IP
address space specified in
[I-D.ietf-softwire-dual-stack-lite], then the IPv6 CE Router
MUST disable the DS-Lite B4 element.
DLW-5: If DS-Lite is operational on the IPv6 CE Router, multicast
data MUST NOT be sent on any DS-Lite tunnel.
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Internet-Draft IPv6 CE router Advanced Requirements July 20115.4.2. 6rd
The IPv6 CE Router can be used to offer IPv6 service to a LAN, even
when the WAN access network only supports IPv4. One technology that
supports IPv6 service over an IPv4 network is IPv6 Rapid Deployment
(6rd). 6rd encapsulates IPv6 traffic from the end user LAN inside
IPv4 at the IPv6 CE Router and sends it to a Service Provider Border
Relay (BR). The IPv6 CE Router calculates a 6rd delegated IPv6
prefix during 6rd configuration, and sub-delegates the 6rd delegated
prefix to devices in the LAN.
The IPv6 CE Router SHOULD implement 6rd functionality as specified in
[RFC5969].
6rd requirements:
6RD-1: If the IPv6 CE Router implements 6rd functionality, the CE
Router WAN interface MUST support at least one 6rd Virtual
Interface and 6rd CE functionality as specified in [RFC5969].
6RD-2: If the IPv6 CE Router implements 6rd CE functionality, it
MUST support user-entered configuration and using the 6rd
DHCPv4 Option (212) for 6rd configuration. The IPv6 CE
Router MAY use other mechanisms to configure 6rd parameters.
Such mechanisms are outside the scope of this document.
6RD-3: If the CE router implements 6rd functionality, it MUST allow
the user to specify whether all IPv6 traffic goes to the 6rd
Border Relay, or whether other destinations within the same
6rd domain are routed directly to those destinations. The CE
router MAY use other mechanisms to configure this. Such
mechanisms are outside the scope of this document.
6RD-4: If 6rd is operational on the IPv6 CE Router, multicast data
MUST NOT be sent on any 6rd tunnel.
5.4.3. Transition Technologies Coexistence
Run the following four in parallel to provision CPE router
connectivity to the Service Provider:
1. Initiate IPv4 address acquisition.
2. Initiate IPv6 address acquisition as specified by [RFC6204].
3. If 6rd is provisioned, initiate 6rd.
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